The present invention relates in general to apparatus for mixing dental amalgams and, in particular, to a new and useful capsule which effectively maintains a separation between a liquid component of the amalgam and a solid component thereof until the two components are mixed together to form the amalgam filling.
Dental amalgam fillings are produced by mixing a liquid component, generally mercury, with a powder component, generally silver or silver alloy powder. The mixed amalgam filling is initially sufficiently fluid so that it can be metered into a tooth to be filled. After a certain period of time, however, the amalgam solidifies, whether it has been utilized or not.
Since the amalgam has only a limited useful life after it has been mixed, capsules have been developed which maintain a separation between the liquid and powder components of the amalgam until the amalgam is to be mixed. The capsules are used in conjunction with an amalgamator which vibrates and/or accelerates the capsule to mix the components with each other.
U.S. Pat. No. 4,450,958 to Prasad discloses a self activated dental capsule which maintains the separation between the liquid component and the powder component by confining the liquid component within a foil container. One portion of the foil container is fixed to the interior of the capsule. The loose powder component of the amalgam is housed within the capsule. By vibrating the capsule, the foil container is ruptured, releasing its liquid component which is then mixed with the powder component to form the amalgam. By holding the container against the interior of the capsule, damage to the container beyond its initial rupturing is avoided. This prevents pieces of the container from becoming admixed with the amalgam.
U.S. Pat. No. 4,632,243 to Muhlbauer discloses a foil package for containing both the liquid and solid components of amalgam. The solid component of the amalgam is in the form of a compressed briquet and the rolls of the foil package are rupturable to release and intermix the liquid and solid components. The foil package is meant for use in conjunction with an outer capsule and a mixing apparatus which vibrates the capsule. Under vibration, the package ruptures, releasing and intermixing its components to form the amalgam. Before the amalgam is utilized, however, the ruptured package must be retrieved from the mixed amalgam.